This invention relates to microwave switches and more particularly to a wideband switchable transmit/receive module.
As is known in the art, it is often desirable to connect a transmitter to a first antenna or alternatively connect the transmitter to a second antenna. In a similar manner, it is desirable to connect the second antenna to a receiver or alternatively connect the first antenna to the receiver. Typically, wideband circulators are employed to provide good impedance matching between the antennas and the transmitter and the receiver as well as to perform the duplexing function. Unfortunately, circulators can be quite large and in missile applications it is necessary to minimize space so that an alternative to circulators is desirable.
Wideband single pole multiple throw and transfer switches as well as cascaded single pole multiple throw (SPMT) switches have also been used to provide the antenna selection in addition to the duplexing (transmit/receive switching) function. A problem with the latter devices is that the amount of insertion loss provided by such devices can be great and for some applications may not be acceptable.
In missile applications, it is also desirable to minimize the radar cross section of the antenna and the missile. Devices that are coupled to the antenna must be properly matched to ensure RF energy is not reflected by the coupled device to the antenna and radiated.